The present invention relates to keyboards, and more particularly to improvements in data entry keyboards and in methods of manufacturing keyboards.
A data entry keyboard includes a number of normally manually operated pushbuttons, commonly called keys, associated with a number of switches so that depression of a key results in operation of a corresponding switch. Such keyboards find many uses including, for example, electronic calculators, programming devices for appliances and industrial controllers and the like, security systems, communications equipment and others.
Typical keyboards of the type known in the past include a switching array comprised of a number of switches. An array of pushbutton keys overlies the switches so that depression of a selected key results in operation of a corresponding switch. Most commonly, each key is discrete from the key array and is formed as a separate part, as by an injection molding process or the like. Consequently, the key array includes structure for retaining and for mounting each key for movement relative to its associated switch.
Use of separate, discrete keys and the associated retaining and mounting structure results in a complex and expensive assembly. Difficulties may be encountered not only in properly positioning the keys during manufacture but also in preventing jamming of keys during use of the keyboard. Moreover, due to the expense of molding or otherwise fabricating a number of discrete parts for a given keyboard assembly, known production methods are not well adapted to frequent modifications such as are associated with the manufacture of small batches or short runs of a given keyboard design.
Among the important objects of the present invention are to provide improvements in keyboards and in keyboard manufacturing methods thereby to overcome the above and other disadvantages of known keyboards and methods. Another important object is to provide an extremely simple and economically manufactured key array and to provide a method for manufacturing such a key array. Yet a further object is to provide a keyboard manufacturing method suited to frequent modifications in keyboard structures and designs. Another object is to provide a keyboard and a key array utilizing a minimum number of parts and avoiding difficulties with key positioning, jamming of keys and the like.
In brief, in accordance with the above and other objects of the present invention, there is provided a keyboard including a switching assembly having a number of switches and a key array overlying the switching assembly. The key array includes a sheet of plastic having upwardly extending projections defining individual keys. Apertures in the sheet of plastic partially surround each key freeing the corresponding key for movement and defining an integral hinge connected between the key and the adjacent portion of the plastic sheet. Each key is provided with a switch actuating structure so that depression of the key results in operation of a corresponding switch.
In accordance with an important feature of the present invention, there is provided a method for manufacturing a keyboard key array. A sheet of plastic is formed into a blank having a plurality of key projections extending upwardly from the top surface of the sheet. The formed sheet, or blank, is then cut to define integral hinges interconnecting the sheet with eacy key projection and to free each key projection for movement relative to the sheet upon flexing of the integral hinges.